Question

我有一个带有6个按钮的视图控制器，它们全部转移到具有表视图的另一个视图控制器。根据按下的按钮，使用表视图将不同的值传递给视图控制器：

@IBAction func englishButton(_ sender: Any) {
    valueToPass = "English"
}


@IBAction func scienceButton(_ sender: Any) {
    valueToPass = "Science"
}

@IBAction func historyButton(_ sender: Any) {
    valueToPass = "History"
}


@IBAction func foriegnLanguageButton(_ sender: Any) {
    valueToPass = "Foriegn Language"
}


@IBAction func mathButton(_ sender: Any) {
    valueToPass = "Math"
}


@IBAction func otherSubjectsButton(_ sender: Any) {
    valueToPass = "Other Subjects"
}

override func prepare(for segue: UIStoryboardSegue, sender: Any?){

    if (segue.identifier == "english") {
        // initialize new view controller and cast it as your view controller
        let viewController = segue.destination as! BuyMenuController
        // your new view controller should have property that will store passed value
        viewController.passedValue = valueToPass
    }
    if (segue.identifier == "science") {
        // initialize new view controller and cast it as your view controller
        let viewController = segue.destination as! BuyMenuController
        // your new view controller should have property that will store passed value
        viewController.passedValue = valueToPass
    }
    if (segue.identifier == "history") {
        // initialize new view controller and cast it as your view controller
        let viewController = segue.destination as! BuyMenuController
        // your new view controller should have property that will store passed value
        viewController.passedValue = valueToPass
    }
    if (segue.identifier == "foriegnLanguage") {
        // initialize new view controller and cast it as your view controller
        let viewController = segue.destination as! BuyMenuController
        // your new view controller should have property that will store passed value
        viewController.passedValue = valueToPass
    }
    if (segue.identifier == "math") {
        // initialize new view controller and cast it as your view controller
        let viewController = segue.destination as! BuyMenuController
        // your new view controller should have property that will store passed value
        viewController.passedValue = valueToPass
    }
    if (segue.identifier == "otherSubjects") {
        // initialize new view controller and cast it as your view controller
        let viewController = segue.destination as! BuyMenuController
        // your new view controller should have property that will store passed value
        viewController.passedValue = valueToPass
    }
}

这里的问题是每当我按下scienceButton时，传递给下一个视图控制器的值都是nil或者在它之前传递的值。再次点击时，传递的值是＆＃34;科学＆＃34;喜欢它的假设。这只发生在那个按钮上，任何想法为什么会发生这种情况？（我已尝试使用if-else if结构设置它。）

Answer 1

您不应将@IBAction方法与直接链接到Interface Builder中的操作的segue结合使用，因为可以在执行函数之前执行segue。

您应该将segue链接到视图控制器对象，并在设置变量后以@IBAction函数以编程方式执行它。

在一个UIAction按钮上传递滞后的价值

1 个答案: